THE MOUSE DEER OF THE RHIO-LINGA ARCHIPELAGO : 

 A STUDY OF SPECIFIC DIFFERENTIATION UNDER 

 UNIFORM ENVIRONMENT. 



By Gerrit S. Miller, Jr. 

 Curator, Division of Mammals, U. S. National Museum. 



The mouse deer are small Ungulates forming a special group, the 

 Tragulida'^ somewhat intermediate in anatomical characters betAveen 

 the deer, camels, and pigs. Two living genera are known, the Indian 

 and Malayan Tragulus and the AVest African Ilyomoschus. In ap- 

 pearance the larger members of the family show some resemblance 

 to the musk deer; while the smaller species of Tragulus^ wdiich 

 scarcely exceed a rabbit in size, suggest an Agouti with unusu- 

 ally long legs. Among the Malayan members of the family two 

 groups of species are found, the larger napus and the smaller kanchils, 

 distinguished from each other by differences in size comparable to 

 that between hares and rabbits, and by certain other slight peculiari- 

 ties. On the Malay Peninsula and the larger islands members of these 

 two groujjs appear everywhere to occur together, but on the smaller 

 islands either may be absent. At no single locality have tw^o forms 

 of the same group yet been found." 



In habits as well as in appearance the Malayan TragnUdrv show a 

 curious analogy to the South American agoutis. They are nocturnal 

 and they live in jungle, where, owing to the denseness of the under- 

 growth, they are seldom seen, but where they may be readily caught 

 with snares set in their runw^ays. So perfectly protected from obser- 

 vation are these animals that I have been unable to find any detailed 

 published account of their habits. Even the field notes of Dr. W. L. 

 Abbott, to whose explorations of the Malay Archipelago most of our 

 knowledge of the species is due, contain no definite observations, a fact 

 that becomes especially significant when it is recalled that his col- 



'^ With the single exception of Pulo Mansalar, Tapanuli Bay, western Sumatra, 

 where two species of napus, Trayulns ainaiius and T. juyuhtris, apparently occur 

 together. 



Proceedings U. S. National Museum, Vol. 37.— No. 1695. 

 Proc.N.M. vol.37— 09 1 1 



